Energy absorbing structures for underbody blast protection

ABSTRACT

The present technology regards a de-coupled V-hull structure for use with an armored vehicle, and energy absorbing crush elements suitable for mounting the V-hull structure in a de-coupled manner to the vehicle. The energy absorbing V-hull structure includes a sloped armor structure forming a cavity having a v-shaped cross-section and a plurality of reinforcing elements, including a backbone, hull stiffeners and lateral supports. The elements are coupled together and supported by energy absorber mounts, extending along each side of the structure. Crush elements suitable for decoupling the V-hull structure are also disclosed, having a uniquely designed housing, a plurality of plates positioned within the housing, and affixation means for securing the crush element to the underside of the vehicle and to the top of the V-hull structure.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under agreement with theOffice of Naval Research, Contract No. N00014-12-C-0497. The Governmenthas certain rights in the invention.

BACKGROUND OF THE TECHNOLOGY

The disclosed technology regards energy absorbing structures forunderbody blast protection. More specifically, the disclosed technologyincludes novel energy absorbing cruciform crush elements (CCE) and ade-coupled V-hull structure attachable to a vehicle by crush elements,such as the energy absorbing cruciform crush elements disclosed.

To protect military vehicles from destruction, and passengers frominjury when subjected to underbody mine or improvised explosive device(IED) attacks, V-hull structures are incorporated into and coupled withthe underside of wheeled armored personnel carriers (APCs), infantrymobility vehicles and infantry fighting vehicles (IFVs). By theirdesign, upward directed blasts are deflected away from the vehicle.Further, the angular faces of the V-hull increase the amount of materiala ballistic projectile must pass through in order to penetrate thevehicle.

V-hulls are typically coupled with the vehicle's monocoque orbody-on-frame chassis, or even directly to the crew compartment. Inlight armored vehicles (5-10 tons), where underbody blasts create largevertical loading, V-hulls can currently resist projectile breaching, butthey quickly transmit vertical loads into the crew compartment. In somearmored vehicles, seat and floor structures are provided with energyabsorption components to mitigate injuries to crew from underbodyblasts; however, occupants can still suffer severe injury.

The present technology improves survivability of lightweight armoredvehicles and reduces injury to its crew by absorbing energy before it istransmitted to the vehicle/crew compartment, wherein the underbody hullcomprises energy absorbing reinforcing elements, being de-coupled fromthe crew compartment using energy absorbing (EA) structures. This novelapproach of decoupling the V-hull by crush elements can work withcurrently available technology, such as EA seating and flooring, tofurther enhance survivability.

By the V-hull's de-coupled attachment to the vehicle and its novelreinforcing structure and configuration as herein described, asignificant decrease in blast-induced accelerations transmitted to thecrew compartment of a vehicle can be achieved. Further, the EA crushelements provide a uniform and effective crush, absorbing energy fromthe blast; and the novel sliding affixation of the crush elements to theV-hull as hereinafter described further mitigate blast-inducedstructural motions.

GENERAL DESCRIPTION OF THE TECHNOLOGY

The disclosed technology regards an energy absorbing crush element forcoupling a V-hull to the underside of a vehicle, and an energy absorbingV-hull structure intended to be de-coupled to the underside of avehicle.

The crush element of the disclosed technology includes a housing, aplurality of plates positioned within the housing, and means forsecuring the crush element to both the underside of the vehicle and tothe top of a V-hull.

The housing of the crush element is in the geometrical shape of atruncated rectangular pyramid, with a cross-sectional area decreasingfrom its base to its top, to provide stability of the element and itscrush when subjected to off-axis loads. Each side of the housing has ahorizontal surface cavity formed thereon to guide a uniform crush of theelement when subjected to a blast or load. By its location, this surfacecavity dictates the location of the first buckle of the crush elementwhen subjected to a blast-induced load, and controls the uniform crushof the element; by its size and with other features of the crushelement, the cavity further controls the load at which buckling willbegin. Further, two sides, opposing one-another, have an openingextending from the base of the housing up through the surface cavity, toadjust the crush load of the element, facilitate its deformation whensubjected to a blast or load, and allow access to securing nuts or othersecuring means within the housing for affixation to the vehicle and thehull structure.

The plates are sized to fit within the housing, and include a top plate,a base plate and one or more cruciform plates. Apertures in the topplate receive threaded studs for affixation to corresponding mountingplates positioned along the sides of the vehicle floor. The mounting ofsuch elements at the vehicle sidewalls, between the floor of the vehicleand the hull, directs blast-induced loads away from the vehicle floor.Oblong apertures (or slots) in the base plate receive bolts foraffixation to the V-hull, and allow lateral movement of the crushelement relative the V-hull when subjected to load or blast, furtherabsorbing energy from the blast and facilitating additional energyabsorption by the V-hull structure. The cruciform plates are affixedwithin the housing to increase load tolerance and facilitate uniformcrush of the element when subjected to a blast, wherein the element willbuckle in a controlled manner, above and below each of the cruciformplates, when subjected to a load (rather than an uncontrolled bucklingout). With two cruciform plates affixed within the interior channel ofthe element, the element can uniformly crush with three buckles, andthereby absorb energy while retaining structural integrity to maintainde-coupled affixation of the V-Hull to the vehicle.

The novel EA crush element mitigates blast-induced structural motionswith its designed crush load, total energy absorbed, geometry and itssliding attachment to the V-hull, and functions well with both axial andhigh off-axis loads.

The energy absorbing V-hull structure of the disclosed technologyincludes a sloped armor structure forming a cavity having a v-shapedcross-section. The structure further includes a plurality of reinforcingelements to resist lateral and longitudinal buckling of the hull,including a backbone extending longitudinally at the base of the armorstructure, hull stiffeners affixed at one end to the backbone andextending laterally toward the top edges of the hull, and lateral energyabsorbing supports, extending across the top of the V-hull cavity. Thebackbone improves the centered blast survivability of the hull byreducing plate deformation, restraining longitudinal deformation and bymaintaining connection to the hull stiffeners. The hull stiffenersrestrain lateral deformation of the V-hull plate. The lateral energyabsorbing supports resist hull expansion when subjected to a blast. Thereinforcing elements may be constructed from high specific strengthsteel and stiffness/bendability, with thin walls, to facilitate energyabsorption and maintain some integrity of the structure when subjectedto blast-induced loads.

EA mounts are also provided, extending along each side of the V-hullstructure, designed to couple with a plurality of EA crush elements. Themounts may be a pair of solid beams designed to receive an edge of thehull, and support and secure the hull stiffeners, the lateral energyabsorbing supports, and the crush elements. The beams are secured to thestructure by mount bolts extending through apertures in the beams andthe hull. When subjected to a blast, the beams stiffen the edges of thehull and transfer the blast-induced load from the lateral stiffeners tothe EA structures.

The de-coupled V-hull structure of the disclosed technology enables theEA crush element to function as designed, with a specialized mount forthe cruciform crush elements to grip the V-hull and the hull stiffeners.By these configurations the EA crush elements and the V-hull structurewithstand blast loads, including high off-axis loads, absorbing energytherefrom, thereby significantly reducing blast-induced acceleration atthe vehicle floor and seats of the crew compartment.

DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present technology, and theattendant advantages and features thereof, will be more readilyunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a peripheral view of an embodiment of the EA crush element ofthe disclosed technology.

FIG. 2 is a disassembled view of the embodiment of the crush elementshown in FIG. 1.

FIGS. 3A and 3B are perspective views of an embodiment of the energyabsorbing V-hull structure of the disclosed technology.

FIG. 4A shows Force-displacement response of CCE in the axialconfiguration, and FIG. 4B shows Force-displacement response of CCE inthe 13° off-axis configuration.

FIG. 5A shows Crush energy versus displacement response of CCE in theaxial configuration, and FIG. 5B shows Crush energy versus displacementresponse of CCE in the 13° off-axis configuration.

FIG. 6 depicts a test configuration for the disclosed technology, andsimulated results from axial and off-axis blasts.

FIG. 7 depicts test results from a simulated test measuring tibia loadswhen subjected to blast, applying centered and off-centered loads, withand without the EA crush element of the disclosed technology.

DETAILED DESCRIPTION OF THE TECHNOLOGY

The disclosed technology regards an energy absorbing crush element forcoupling a V-hull to the underside of a vehicle, and an energy absorbingV-hull structure intended to be de-coupled to the underside of avehicle. Embodiments of the disclosed technology and components thereofare shown in FIGS. 1-2. Following is a detailed description of thetechnology and embodiments thereof, concluding with results fromsimulated and actual testing of the disclosed technology, demonstratingits effectiveness at absorbing blast-induced energy while maintainstructural integrity.

Energy Absorbing Crush Element

The present technology regards an energy absorbing crush element forcoupling a V-hull to the underside of a vehicle, an embodiment of whichis shown in FIGS. 1 and 2. As shown in the figures, the crush element100 includes a housing 110 in the shape of a truncated rectangularpyramid having an interior channel, and a plurality of plates affixedwithin the channel, in a parallel configuration.

In some embodiments, such as the embodiments shown in FIGS. 1 and 2, thehousing 110 is in the geometrical shape of a truncated square pyramid,with rounded edges extending inwardly, up from the base at an angle(e.g., 5.7°) from vertical. In the embodiment shown, the housing has aheight of about 7.25″, with a base width of about 6″, and a top width ofabout 4.5″. Other similar dimensions may be suitable, based upon thesize and weight of the vehicle and the V-hull. For purposes ofdescribing embodiments of the EA crush element, reference is made to amidplane and a quarterplane of the housing, meaning the planes extendinghorizontally across the interior channel of the housing, at the midpointand quarterpoint of its height from the base, respectively.

The housing 110 may be constructed from a pair of plates 115, 116, eachplate being twice bent to form one side of the housing, edges andcorresponding halves of adjacent sides of the housing. In thisembodiment the plates are affixed to each other, by welding, at theirrespective ends to form the truncated rectangular pyramid of thehousing.

Formed on each side of the housing is a horizontal indent or surfacecavity 111, positioned at or below the midplane of the housing. In theembodiment shown in FIGS. 1 and 2, the surface cavity 111 is about 0.5″below the midplane of the housing. The surface cavity shown in thisembodiment has a width of about 4″, a height of about 0.6″ and a depthof about 0.2″; other similar dimensions may be suitable, based in partupon the size of the housing. The position of the cavity should be thesame on each side of the housing to facilitate a uniform crush of theelement when subjected to a blast-induced load.

One or more sides of the housing 110 may have similarly sized openings112. As shown in the embodiment of FIGS. 1 and 2, the openings 112 maybe on two opposing sides, having a width of about 3.4″ at the base ofthe housing, and extending through the surface cavity 111 (therebybisecting the cavity) at the same angle as the angle from vertical ofthe housing edges. The size of the opening, with other features of thecrush element, determines the load at which the element begins to crushand the crush load; the wider the opening, the lower the loads.

The crush element further comprises a plurality of plates affixed to thesides of the housing, across its interior channel, including a top plate120, one or more cruciform plates 131, and a base plate 140. As shown inFIG. 1, the top plate 120 is affixed within the top of the housing 110,to form a planar top surface of the crush element 100 with the top ofthe housing. The top plate 120 may comprise a plurality of tapped holesor apertures to receive threaded studs 125, allowing coupling of theelement to a vehicle frame, chassis or underbody by means of thethreaded studs.

Similarly, as shown in FIG. 1 the base plate 140 is affixed within andforms the bottom surface of the crush element 100, with the edge of thehousing 110. The base plate comprises a plurality of apertures 141, asshown in FIG. 2, allowing coupling of the element to a V-hull structure,as hereinafter described. In the embodiment shown the apertures areoblong in shape (or slots) to allow lateral movement of the element 100relative the V-hull when subjected to load or blast. The bottom and/ortop surface of the base plate may further comprise a layer of lowfriction material, such as glass PTFE (polytetrafluoroethylene) tape,bonded or otherwise affixed thereto to facilitate movement of theelement 100 relative to the V-hull, causing a more uniform crush of theelement when subjected to off-axis blasts. Likewise, the securingstructure, such as washers, may be coated with a similar layer of lowfriction material, to further facilitate such movement of the element100 relative to the V-hull.

One or more cruciform plates are affixed within the housing channel ofthe disclosed technology. As shown in the embodiment of FIGS. 1 and 2,two cruciform plates 131, 132, are affixed to and positioned within theinterior channel of the housing 110. The cruciform shape of these platesis designed so that the void corners accommodate the rounded edges ofthe housing and allow the ends of the cruciform plates to be securedwithin the housing. In this embodiment, the first cruciform plate 131 isaffixed at about the midplane of the housing, and the second cruciformplate 132 is affixed at about the quarterplane of the housing. Becausethe cross-sectional dimensions of the housing decreases from the base tothe top of the housing, each plate 131, 132 is sized so that it may beaffixed at its ends to the housing, at the desired position.

Each of the housing 110 and the plates 120, 131, 132 and 140, may beconstructed from stainless steel, such as 304L stainless steel, having athickness of between 9-11 gage, although a thinner gage would besuitable when crush is desirable at lower loads, and a thicker gagewould be suitable when design dictates a higher load crush threshold.The edges/ends of the plates 120, 131, 132 and 140 may be beveled, andthe interior walls of the housing 110 may comprise a plurality ofgrooves, to facilitate through-thickness beveled welds of each platewithin the channel of the housing 110.

To allow affixation of the crush element 100 to the underside of avehicle, a plurality of threaded studs 125 as shown in FIGS. 1 and 2 maybe provided, extending through the apertures 121 in the top plate, andsecured to the underside of the plate by means of a nut or othersecuring structure. Similarly, to allow affixation of the crush elementto a V-hull, a plurality of bolts 255 may be provided, extending throughthe apertures 141 of the base plate, and secured on the inner surface ofthe base plate by means of a washer and nut, or other securingstructure.

The described energy absorbing crush element, by its structure andconfiguration, provides a novel structural energy absorber for underbodyblast mitigation in the form of a cruciform crush element. The shape andposition of the housing with the surface indents and the cruciformplates facilitate an engineered crush load, providing good actuation andlarge off-axis loading, capable of absorbing high tensile loads as wellas compression loads while maintaining structural integrity through andafter the crush. Embodiments of the crush element described herein havean engineered crush load of between about 90 and 140 kips depending onthe loading rate and degree of off-axis loading, and are believed to becapable of handling off-axis loading at least up to 13 degrees off theaxis. Further, the EA crush elements of the disclosed technology havegood structural strength and stiffness in general service, and arecapable of withstanding harsh environments (e.g., heat, corrosionresistance, dirt).

Based upon simulated and actual testing, embodiments of the crushelement of the disclosed technology triggers and manages elementbuckling (crush) in the range of 90 to 140 kips. This controlledbuckling was proven in both an axial drop test and a 13° off-axis droptest. Shown in FIG. 4 are results from real and simulated quasi-static(QS) and drop tests, showing the axial force versus displacement (crush)of the crush element. The simulation results show good agreement withthe actual tests. Total energy absorbed as a function of stroke(displacement) for these real and simulated tests are shown in FIG. 5.As revealed by these results, the simulated response closely matchestest results allowing accurate prediction of their performance when usedin vehicles. Post-crush, the elements showed good structural integrityso that after subjected to a blast, the V-hull remains affixed to thevehicle by means of the crushed elements.

De-Coupled V-Hull Structure

The present technology further regards an energy absorbing structureintended to be de-coupled to the underside of a vehicle, for underbodyblast protection. As shown in FIGS. 3A and 3B, this energy absorbingstructure 200 includes a reinforced sloped armor structure or hull 210forming a cavity having a v-shaped cross-section, and extending toopposing edges. The energy absorbing structure 200 further includesenergy absorber mounts 250 designed to couple with energy absorbingcrush elements 100, such as those described above, which elements couplewith a vehicle.

The hull 210 is made from aluminum armor (such as 5083-H131), andprovides ballistic protection to the exterior surface of the energyabsorbing structure, deflecting projectiles from the vehicle. In thisembodiment the hull has a width of about 65″, a height of between 15-16″and a depth of about 75″. As shown in FIGS. 3A and 3B, the hull 210 isreinforced by multiple reinforcing elements, including a backbone 220, aplurality of stiffeners 230, and a plurality of lateral energy-absorbingsupports 240. The reinforcing elements are not affixed directly to thehull 210.

The backbone 220 may be one or more beams or tubes made from highlydeformable, high strength steel, extending longitudinally at the base ofthe hull. In the embodiment of the disclosed technology shown in FIGS.3A and 3B, the backbone is formed from two rectangular tubes (such asSTRENX 700 thin-walled tubes, manufactured by SSAB), laterally weldedtogether. The backbone may include a support structure, such as a pairof smaller, energy absorbing tubes 215, affixed lengthwise at the centerof the backbone's undersurface, and extending along the length of thebackbone. In the embodiment shown each energy absorbing tube 215 isattached to one of the rectangular tubes of the backbone 220. The tubes215, which may be made from stainless steel, have a height designed tomaximize the crush distance of the tubes 215 between the hull 210 andthe middle of the backbone 220. By this structure and configuration, thecrush of the EA tubes 215 absorb energy from blast-induced loads fromthe deforming hull 210 and transfer the loads more gradually to thebackbone 220.

As shown in FIGS. 3A and 3B, the hull 210 is further reinforced by aplurality of hull stiffeners 230, each stiffener being affixed at oneend to the backbone 220, and extending laterally on each side of thehull 210 toward its top edges. The hull stiffeners may also be STRENX700 thin walled tubes providing high specific strength and stiffness, aswell as high bendability to absorb blast loads.

Lateral energy-absorbing supports 240 also reinforce the hull, extendingacross the top of the V-hull cavity. As shown in FIGS. 3A and 3B, thelateral supports may have a dogbone shape, and are designed to absorbenergy by deforming plastically as the hull deforms outwards whensubjected to a blast or load, thereby restraining lateral V-hulldeformation. The lateral energy-absorbing supports may be made fromsteel, such as A572 Grade 50 steel.

The hull 210, and the reinforcing elements 230 and 240, are coupled toform the energy absorbing structure 200 by energy absorber mounts 250,extending along each side of the structure 200. As shown in theembodiment of FIGS. 3A and 3B, the mounts 250 may include a pair ofsolid beams 251, 252, removably affixed about the edges of the hull 210.Each of the beams 251, 252 has a corresponding angular recess extendingalong its length to receive an edge of the hull 210. As shown in FIGS.3A and 3B, the top beam 251 may have an angled interior edge to abut theupper end of the hull stiffeners 230. The beams 251, 252 are affixedtogether, about the edge of the hull, by mount bolts 255 extendingthrough corresponding apertures in the beams and the hull, the mountbolts being secured by nuts or similar securing structure. The beams maybe made from a lightweight metal, such as aluminum 6061-T6.

In the embodiment of FIGS. 3A and 3B, the hull stiffeners 230 aresecured to the top beam by means of a bent plate 256, with an inclinedportion thereof positioned on top of each stiffener, at its end, and aplanar portion extending over the surface of the top beam 251. The platemay be affixed to the top surface of the stiffener by means of aplurality of bolts (secured by nuts or other securing means) extendingthrough corresponding apertures in the stiffener surface, and may besecured to the top beam 251 by the mount bolts 255.

FIG. 3 further depicts a manner of affixing the lateral energy absorbingsupports to the beam 251 by means of affixation bars (or gussets) 245,wherein the lateral supports have planar recesses at each end to receivean end of the affixation bar. In this embodiment the affixation bars andlateral energy absorbing supports have a plurality of correspondingapertures to allow affixation of the bar to the top beam 251 (by meansof the mount bolts 255), and to the lateral supports, by means of aplurality of bolts secured by nuts or similar securing structure.

Finally, in the embodiment of the disclosed technology shown in FIGS. 3Aand 3B, the hull stiffeners 230 and the lateral energy absorbingsupports 240 are alternatingly positioned along the length of the hull210, with the EA crush elements 100 slidingly secured to the mounts 250,above the plates 251, by means of the mount bolts 255.

Simulated nonlinear dynamic finite element analysis (FEA) of blasts onthe V-hulls of the disclosed technology, secured to a test structure bymeans of the EA crush elements of the disclosed technology wereconducted for high explosives buried in wet sandy gravel. As shown inFIG. 6, the crush elements of the disclosed technology were mounted to atest surrogate, representing the weight of a light armored vehicle, onthe underside of the doorsill. Results from two configurations are shownin the figure, one with the blast centered under the V-hull and thesecond with the blast offset one quarter of the width of the V-hull.Both cases show uniform crushing of the crush elements along the lengthof the V-hull. Further, it is evident that deformations of the underbodyV-hull structure are isolated from the crew cab floor, and there waslittle doorsill motion which could cause injurious floor displacements.

Further, based upon simulated testing of the EA crush elements of thedisclosed technology, it is evident that the use of such elements withv-hull structures significantly reduces tibia loads to below injuryassessment reference values (IARV) for significant injury to the tibia.Results of this simulation are shown in FIG. 7, wherein the first andthird bar for each tibia index are without the EA crush element, whilethe second and fourth bars are with the EA crush element; the first twobars used a 10 kg centered blast, while the third and fourth bars usedan 8 kg off centered blast.

While the form of apparatus herein described constitutes preferredembodiments of the present technology, it is to be understood that theinvention is not limited to this precise form of apparatus, and thatchanges may be made therein without departing from the scope of theinvention that is defined in the appended claims.

The invention claimed is:
 1. An underbody hull for use with an armoredvehicle, the structure comprising an armor hull structure forming acavity and extending to opposing edges; and a plurality of reinforcingelements, comprising: a backbone comprising one or more tubularreinforcing structures extending longitudinally at a base of the armorhull structure, and a plurality of hull stiffeners, each comprising atubular reinforcing structure, extending laterally toward top edges ofthe armor hull structure, wherein each of the hull stiffeners areaffixed at one end to the backbone.
 2. The underbody hull of claim 1,wherein the reinforcing elements are detached from the armor hullstructure.
 3. The underbody hull of claim 1, wherein the armor hullstructure cavity has a v-shaped cross-section, is made from aluminum,and is de-coupled from the vehicle.
 4. The underbody hull of claim 1,wherein the backbone comprises a first pair of tubes, and the tubes ofthe backbone are adjoined.
 5. The underbody hull of claim 4, wherein thetubes of the backbone are made from highly deformable, high strengthsteel.
 6. The underbody hull of claim 4, wherein the backbone furthercomprises a second pair of tubes, affixed lengthwise at a center to anundersurface of the backbone.
 7. The underbody hull of claim 1, thereinforcing elements further comprising a plurality of lateral energyabsorbing supports, extending across the top of the armor hull structurecavity.
 8. The underbody hull of claim 7, wherein the hull stiffenersand the lateral energy absorbing supports are alternatingly positionedalong the length of the armor hull structure.
 9. The underbody hull ofclaim 7, further comprising energy absorber mounts extending along eachside of the armor hull structure.
 10. The underbody hull of claim 9,further comprising a plurality of energy absorbing crush elementssecured to the energy absorber mounts.
 11. The underbody hull of claim10, wherein the energy absorbing crush elements are positioned lateralto the hull stiffeners, and secured to the energy absorber mounts bymeans of mount bolts.
 12. The underbody hull of claim 11, wherein thelateral energy absorbing supports are coupled to the energy absorbermounts by means of affixation bars, and wherein the affixation bars aresecured to the energy absorber mounts by means of mount bolts.
 13. Theunderbody hull of claim 9, wherein each of the energy absorber mountscomprise a top beam and a bottom beam, and wherein each of the top andbottom beams have a corresponding angular recess extending along itslength to receive an edge of the armor hull structure.
 14. The underbodyhull of claim 13, wherein the hull stiffeners are secured to the energyabsorber mounts by means of a bent plate, having an inclined portionpositioned on top of each hull stiffener at an end, and a planar portionextending over the energy absorber mount secured to the mount by mountbolts.
 15. An underbody hull for use with an armored vehicle, thestructure comprising an armor hull structure forming a cavity andextending to opposing edges; and a plurality of reinforcing elementscomprising a plurality of lateral energy-absorbing supports extendingacross the top of the armor hull structure cavity.
 16. The underbodyhull of claim 15, wherein the lateral energy-absorbing supports have adogbone shape.
 17. The underbody hull of claim 15, wherein thereinforcing elements further comprise a backbone comprising one or moretubular reinforcing structures and extending longitudinally at a base ofthe armor hull structure, and a plurality of hull stiffeners comprisinga plurality of tubular reinforcing structures, extending laterallytoward top edges of the armor hull structure, wherein each of the hullstiffeners are affixed at one end to the backbone.
 18. The underbodyhull of claim 15, further comprising energy absorber mounts extendingalong each side of the armor hull structure, wherein each of the energyabsorber mounts comprise a top beam and a bottom beam, and wherein eachof the top and bottom beams have a corresponding angular recessextending along its length to receive an edge of the armor hullstructure.
 19. The underbody hull of claim 18, further comprising aplurality of energy absorbing crush elements secured to the energyabsorber mounts.
 20. An underbody hull for use with an armored vehicle,the structure comprising an armor hull structure forming a cavity andextending to opposing edges; a plurality of reinforcing elements; and apair of energy absorber mounts extending along each side of the armorhull structure, wherein each of the energy absorber mounts comprise atop beam and a bottom beam, and wherein each of the top and bottom beamshave a corresponding angular recess extending along its length toreceive an edge of the armor hull structure and is removably secured,about the edge of the armor hull structure.
 21. The underbody hull ofclaim 20, wherein the reinforcing elements comprise a plurality oflateral energy-absorbing supports extending across a top of the armorhull structure cavity, and coupled with the energy absorber mounts. 22.The underbody hull of claim 20, wherein the reinforcing elementscomprise a plurality of tubular reinforcing structures.
 23. Theunderbody hull of claim 22, wherein the tubular reinforcing structurescomprise a backbone extending longitudinally at a base of the armor hullstructure, and a plurality of hull stiffeners extending laterally towardtop edges of the armor hull structure, wherein each of the hullstiffeners are affixed at one end to the backbone and at an other end toone of the energy absorber mounts.
 24. The underbody hull of claim 20,further comprising a plurality of energy absorbing crush elementssecured to the energy absorber mounts.